FA5695 Datasheet, PDF (19/21 Pages) Fuji Electric – Fuji Switching Power Supply Control IC

FA5695
(6) Terminal No. 6 (GND terminal)
Function
This voltage of GND terminal is the reference for each portion of whole
circuits.
(7) Terminal No. 7 (OUT terminal)
Function
This drives MOSFET.
Application
- Wiring
Connect it to the gate terminal of MOSFET through resistance.
- Operation
During the period when turn on MOSFET, the output state is high, and
the output voltage is almost VCC.
During the period when turn off MOSFET, the output state is low, and the
output voltage is almost 0V.
- Additional explanation
The gate resistor is connected to limit the current of the OUT terminal
and prevent oscillation of the gate terminal voltage. The rating of the
output current is 1.0A for source and 1A for sink.
Using the connections shown in Fig. 23 and Fig. 24, it is possible to
independently set the gate driving current of turning on and off MOSFET.
(8) Terminal No. 8 (VCC terminal)
Function
(i) Supply the power of IC.
Application
- Wiring
Connect the start up resistor R7 between VCC terminal and Voltage line
after rectifying from AC line, which supplies power before IC starts
switching operation.
In general application, the power is provided from the auxiliary winding
of the transformer through D2 during operation.
In some application, DC power supply can be connected.
- Operation
In the application with out DC power supply to feed VCC terminal, the
current through start up resistor R7 charges the smoothing capacitors
C5 and C9, and when VCC voltage rises to the on threshold voltage of
UVLO, the IC starts operating. Before starting operation, it is necessary
to supply current higher than 80uA (max), the startup current of the IC.
During steady operation, the VCC is supplied from the auxiliary winding
of the inductor. (Fig. 25)
When the supply voltage rises from zero, the operation starts at 13V
(typ.).
If the supply voltage decreases after the operation starts, the operation
stops at 9V (typ.) by UVLO. After IC stops operation due to UVLO, the
OUT terminal is Low state to cut off the output.
Additional explanation
UVLO is preventive function to keep the circuit from malfunction when
the supply voltage decreases.
With the start up resistor R7, it is necessary to supply current of 80μA or
higher, the startup current, until start operating, and the following
formula must be satisfied.
2 Vac(min)  Von(max)
R7 
80 10^6
VCC
8
Driver
OUT
7
6
GND
Fig.22 OUT pin circuit(1)
VCC
8
Driver
7
OUT
6
GND
Fig.23 OUT pin circuit(2)
VCC
8
Driver
7
OUT
6
GND
Fig.24 Out pin circuit(3)
L1
R7
C1
D2
C9 C5
8
VCC
Fig.25 VCC pin circuit(1)
8
VCC
外^Ex部^terD^naC^l 電^DC源
Power Supply
C9 C5
Fuji Electric Co., Ltd.
AN-073E Rev.1.1
April-2011
Fig.26 VCC pin circuit(2)
http://www.fujielectric.co.jp/products/semiconductor/
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